534 CHARACTERS OF PRIMATES CHAP, group to which so many others appear to converge. It is dis- puted, for example, whether the Chiiacidae among extinct Lemurs are rightly placed, or whether they should be referred to the Creodonta. The number of primitive characters seen among the Primates, even In Man himself, is remarkable. Of these the more important are the five digits of both limbs arid the plantigrade walk, the presence of clavicles and of a centrale, and the absence of a third trochaiiter. All these features distinguish the early Eutheria. SUB-ORDER 1. LEMIIHOIDEA.1 The animals known as Lemurs, from their nocturnal and ghostly habits, are on a lower level of organisation than the other division of the Primates. Even the external form enables the members of the present sub-order to be readily distinguished from the higher Anthropoidea. The head is more like that of a Pox, with a sharp muzzle; it lacks the human expression of the face of even the lower among the Apes. The long tail is never prehensile, and there is never any trace of cheek pouches or of integumental callosities, which are frequently so characteristic of the Apes. The Lemurs agree with the remainder of the Primates in having pectoral mammae (sometimes abdominal ones are present in addition, and in Hapalemwr---in the male at least---there is a mamma upon each shoulder), in having opposable thumbs and toes, and in the flattened digits. The tail varies from complete absence (in the Loris) to a great length and bushiness in the Aye-aye. The pectoral limbs are always shorter than the hind-limbs; the reverse Is occasionally the case in the Anthropoidea. A curious contrast between the two divisions of the Primates concerns the digits of the hands arid feet. In the Anthropoidea it Is the hallux or pollex -which is subject to great variation. In the Lemurs, on the contrary, the thumb and great toe are always well developed, but the second or the third digit constantly shows some abnormality; thus the singular elongation of the third digit of the hand in Chiromys and the absence of .the index in the Potto.2 In all Lemurs the 1 See Dr. Hivart's papers in Proc. Zool. Soc. 1864, -65, -66, -67, and -73 for osteology and teeth. a Mime an<l Mivart, Trans. Zool. Soc. vii. 1869, p. 1.